The two wheels per side are attached to a central pivot point. And then each side is attached through a linkage in the body that allows the rover to passively have body averaging (similar to a gear differential) this lets the rover climb over rocks and maintain great stability.

One big consideration for lunar solar panel design is whether the mission is on the equator or near the poles. A polar mission would want the solar panels to be vertical. While a equatorial mission would want the panels to be horizontal.

The other big obstacle to solar panel design is to have space to radiate heat so you do not destroy the rovers components.